The invention is based on a process for cold-start control in an electronic internal combustion engine system with signal generating stages for the fuel metering wherein an increased fuel proportioning is effected during starting, possibly with simultaneous or subsequent injection quantity control, a predetermined quantity of consecutive cold start short-duration injection pulses (ti*) which exceeds by a multiple the quantity of injection pulses (ti) normally issued during conventional cold starting per time unit, and/or per quantity of revolutions, and/or per quantity of ignition times, is fed per every ignition time interval to an end stage for controlling the injection valve or valves, and the generation of the quantity of cold start short-duration injection pulses (ti*) is interrupted as the ignition time intervals due to speed increase become shorter. The invention also relates to an electronic internal combustion engine control system for carrying out the process. Measures for cold-start control or cold-start boosting in fuel metering systems assigned to internal combustion engines, for instance fuel injection systems, carburator and the like, are known (German Auslegeschrift 2,511,974; German Offenlegungsschrift 3,042,245). The known systems are designed in such a way that, while starting an internal combustion engine, in particular in the lower temperature range, a supplementary feed of fuel is metered to the engine in order to compensate for possible condensation losses owing to cold intake pipe walls and cylinder inner walls. It is likewise known to preset a supplementary feed of fuel in dependence on temperature, in other words to preset initial fuel injection times t.sub.i as a function of ambient temperature during starting and subsequently to reduce the supplementary feed in dependence on engine speed and/or in dependence on time.
A similar presetting applies to the area of ignition, where likewise speed-dependent ignition adjustments during starting are known--more details on this are given in the German Offenlegungsschrift 3,042,245.
In order to meet both the requirement for ever better starting performance and the requirement for minimum possible fuel consumption, and in view of emission regulations becoming more stringent, three different phases for the supplementary fuel feed control and supplementary feed reduction during cold starting are disclosed in German Offenlegungsschrift 3,042,245. In addition, the German document discloses the temperature- and speed-dependent adjustment of the ignition angle. The amount of fuel supplied in this case follows a certain curve, which is plotted either in relation to time or to the speed of the internal combustion engine during starting, which curve may be shaped such that during a first phase a constant supplementary feed of fuel is supplied until a preset number of ignitions or revolutions of the internal combustion engine is reached (plateau region); following the plateau region there is a supplementary feed reduction phase in which the amount of fuel supplied drops linearly or follows steep-drop functions up to a transition region, which commences for example upon reaching an upper starting speed and characterizes the transition into so-called after-starting enrichment or warm running. In a corresponding way, in the ignition system there occurs an increasing advanced adjustment in a lower speed range and a retarded adjustment which becomes greater toward higher temperature.
The preset characteristic curves and functions involved here are sometimes difficult to realize and are also complicated, inasmuch as a speed-dependent function and a function dependent on the number of ignitions have to be taken into account at least in the region of the supplementary fuel feed reduction. At the same time, the number of ignitions in the plateau region (cold-starting range I) has to be taken into account, or, in order to be able to carry out the transition from the plateau region to the supplementary fuel feed reduction, a cold-start speed threshold NKS=f(n) has to be taken into account.
Such a multiplicity of cold-start functions is complex and makes the control systems expensive even if, as is usual in the case of modern computer-controlled internal combustion engine control systems, the respective functions and values can be called from a memory at certain program points.
Furthermore however, the problem arises with the known cold-start control systems that they issue the requisite and calculated amount of fuel according to the respective operating conditions and deliver the fuel only once-per-ignition by a correspondingly adjusted opening of the respective injection valve, which at subzero temperatures can result in the production of a problematic ignitable mixture, particularly in the case of certain engine types (for instance with critical spark plug position); consequently, the adaptation of the cold-start control systems (CSC systems) is often very difficult in the case of certain engine types, owing to the design of the combustion space and the poor spark plug position, so that the cold-start limit at which an internal combustion engine still starts up can also be problematic. The reason for this is that the possibility cannot be excluded that the fuel injected, sometimes in considerable amounts, can also reach the spark plug in liquid form and then extinguish the ignition spark or that an ignitable mixture simply cannot be formed.